[Feature Request]: Support big decimal calculation for Aptos

[element2050]

Is your feature request related to a problem? Please describe.
In Swap scenarios higher precision is needed to avoid large number overflow.
Starcoin already supports U256 natively, Aptos does not support U256 yet.

Describe the solution you'd like
So need degrade of the original U256 to u128, then wait for Aptos to support U256 before accessing and supporting

Describe alternatives you've considered

Additional context